There is a decent answer to inmate dating website that's safe for pen pals, but it needs a caveat first. I judge inmate dating almost entirely on not oversharing now. The part people underrate about inmate dating is vetting people properly.
In practice, inmate dating lives or dies on how it feels to use. In practice, inmate dating lives or dies on the caution people forget. I'd put how many accounts are active above almost everything else when it comes to inmate dating.
Curious whether inmate dating works differently outside big cities? Take that as one data point on inmate dating website that's safe for pen pals, not gospel.
If you want a comparison point on inmate dating, tried Datescout.